Access scaffoding design

7/27/2019 Access scaffoding design

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Manar Al Omran CoCR. No. 4030177499

P.O. Box 46217Jeddah 21532

Tel.: (02) 620-4582, 620-0613

Fax: (02) 620-7194

Job Title : CHEMCIAL STORAGE TANK-YANBU

Subject: Design of external Access Scaffolding Storage Tank

Client:

Contractor:

Prepared by:S M Ali

Date:24-07-2013

CALCULATION SHEET

(STRUCTURAL)

Page | 1

INDEX OF CONTENT

S.NO INDEX OF CONTENT1. SCOPE OF WORK

2. DESIGN PARAMETERS

3. DESIGN CHECK FOR SCAFFOLD PLANK

4. DESIGN CHECK FOR TRANSOMS/BEARERS

5. DESIGN CHECK FOR RUNNER 6. DESIGN CHECK FOR VERTICAL STANDARD

7. LATERAL STABILITY

8. CHECK FOR CAPACITY OF BRACE COUPLER

9. ATTACHMENT

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Tel.: (02) 620-4582, 620-0613

Fax: (02) 620-7194



Client:

Contractor:

Prepared by:S M Ali

Date:24-07-2013

CALCULATION SHEET

(STRUCTURAL)

Page | 2

SCOPE OF WORK

ERECTION/ DISMANTLING AND PERIODIC INSPECTION OF THE ERECTED

SCAFFOLDING FOR ACCESS STORAGE TANK

LOCATION : YANBU

SYSTEM OF SCAFFOLDING : MAO CUPLOCK SYSTEM.

REFERENCES :

(a) SAUDI ARAMCO SCAFFOLD SAFETY HANDBOOK(SSH)

(b) SAES-A-112 METEROLOGICAL AND SEISMIC DATA

(c) AISC(ASD),ASCE-7,BS1139,EN74 etc.

Height of structure : 17.6m(approx from peak point)MAO cuplock system scaffolding : independent run faade

Grid Size : 1.8m x 1.25m (Maximum)

Scaffolding height : 16.6m + 1m(hand rail)

Vertical lift of ledger/transom : 2.00m

Live Load : 2.4 kN/m2(As per ACI 347-6)

DESIGN PARAMETERSMATERIAL

1) MAO Cuplock system scaffolding BS 1139

Outside Diameter'OD' = 48.3mmWall thickness,t = 3.2mm

Yield strength = 235 N/mm

Inner diameter = (48.3-3.2-3.2) = 41.9mmArea of tube = /4 x (48.3- 41.9) = 453.45 mm

Plastic section modulus = (48.3^3 41.9^3)/6 = 6519.76 mm3

Radius of Gyration = Sqrt I/A = 16 mm

Moment of Inertia = /64 x (48.34 - 41.94 ) = 115856.5mm4

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Tel.: (02) 620-4582, 620-0613

Fax: (02) 620-7194



Client:

Contractor:

Prepared by:S M Ali

Date:24-07-2013

CALCULATION SHEET

(STRUCTURAL)

Page | 3

2) Tube as per Bs 1139 specification

Outside Diameter'OD' = 48.3mmWall thickness,t = 3.2mm

Yield strength = 235 N/mm

Weight of tube = 0.035 KN/m

Physical properties of Tube

Inner diameter = (48.3-3.2-3.2) = 41.9mmArea of tube = /4 x (48.3- 41.9) = 453.45 mm

Plastic section modulus = (48.3^3 41.9^3)/6 =6519.76 mm3

Radius of Gyration = Sqrt I/A = 16 mmMoment of Inertia = /64 x (48.34 - 41.94 ) =115856.5mm4

3) Scaffold Plank (LVL Boards),Hy Plank 42mm x 230mm as per OSHA STANDARD

(See attachment)

Weight of scaffold plank = 0.25 KN/m2

Bending stress,Fb = 15.23 MPa.

Shear stress,Fv = 0.863 MPa.Youngs Modulus,Eb = 10563 MPa.

Area of Cross section,(Ab) = 9660 mm2

Section Modulus = 67620 mm3

Moment of Inertia = 1420020 mm4

Safe Bending capacity = 1.03 KN-m

Safe Shear Capacity = 3.34 KN

4) LOADING

Rating of Scaffolding = Medium Duty Rating

Dead load (DL) = Wt of scaffold plank + wt of ledger

Live load(L.L) = 2.4 KN/m2

5) LOAD COMBINATIONS.(See attachment-02)

Gravity Loads

DL + 4 (LL) < Failure (as per SSH) Used to check flexural members.

(scaffold plank,bearers,transom,runners, posts(standards) etc.).

P(DL + LL) < Pf/4; Pf = Ag x Fa (for vertical standards or posts).

DL+ LL (gravity loads) to check capacity of couplers & fittings ref 9.7.2L SSH

(Multiply the rated SWL listed in SSH table II. 9.2 by 0.4 to obtain a safety factor of 4 ans also tocheck the deflection in scaffold boards,Transom/Bearer a Runners).

Wind loads

DL + LL + WL for vertical posts,braces (compression members).

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Tel.: (02) 620-4582, 620-0613

Fax: (02) 620-7194



Client:

Contractor:

Prepared by:S M Ali

Date:24-07-2013

CALCULATION SHEET

(STRUCTURAL)

Page | 4

6) ALLOWABLE FLEXURAL MOMENT (Bearer, Transom, & Runner).

Mf = SIF x Fy (min) x Z

Mf = allowable flexural moment.

SIF = Strength increase factor (Max SIF : 1.20, actual Yield strength as per test result is 375 MPa)Z = Plastic section modulus

Fy = Minimum yield strength = 235 N/mm2

Mf = 1.20 x 235 6520 = 1.838 KN-M

7) ALLOWABLE SHEAR FORCE CAPACITY (Bearer, Transom, & Runner).

Vc = Allowable shear capacity = 0.4 x Fy x SIF x AFy = Minimum yield strength = 235 N/mm

2

A = Area of C/S of tube.

Vc = 0.4 x 235 x 1.2 x (453.45/1000) = 51.15 KN.

8) Load carry capacity of MAO Cuplock standard per vertical leg.

P = 59.376 KN (See Item no :14 )

9) Check Scaffold Plank (Boards)Dead Load (DL) = 0.25 KN/m2

Live Load(LL) light duty = 2.40 KN/m2

Loading W = DL + 4 LL = 0.25 + 4 x 2.4 =9.85 KN/m2

Considering a single plank of 230mm wide strip.Loading /m = 9.85 x 0.23 = 2.2655 KN/m.

Spacing of transom/bearer supporting scaffold plank = 1.25m c/c max (from grid size)

Maximum bending moment = wl2 /8 = 2.2655 x 1.252 /8 = 0.443 KN-mMaximum shear force = wl/2 = 2.2655 x 1.25/2 = 1.42 KN.

Allowable deflection(as per SSH)= L/60 = 1250/60 = 20.833 mmMaximum deflection = 5wl4/384 EI = 5 x 2.2655 x 12504 = 4.83mm(safe)

384 x 10563 x 1420020

(10) Check Transom/Bearer

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Tel.: (02) 620-4582, 620-0613

Fax: (02) 620-7194



Client:

Contractor:

Prepared by:S M Ali

Date:24-07-2013

CALCULATION SHEET

(STRUCTURAL)

Page | 5

Dead Load (DL) = 0.25 KN/m2

Live Load (LL) = 2.4 KN/m2

Self weight of tube = 0.039 KN/m

Load combination

DL + 4 LL.

=0.25 + 4(2.4)= 9.85 KN/m2

Load /m = 9.85 x 0.7(tributary width) = 6.895 KN/m

There fore total load = 6.9 + 0.039 = 6.934 KN/m

Maximum bending moment = wl2/8 = 6.934 x 1.252/8 = 1.36 < 1.838 KN-m

(Mf refer item no 6)

Maximum shear force = wl/2 = 6.934 x 1.25/2 = 4.34 KN < 51.15 KN

(Vc,refer item no 7).

(11) Check Runner ledger 1.8m

Maximum bending moment = 4.3715x0.9 4.34 x0.5 -0.039x 0.9x0.45=1.76 < 1.838 KN-m(Mf refer item no 6)

Maximum shear force = 4.3715KN < 51.15 KN

(Vc,refer item no 7).

(12) Check Vertical Post(MAO Cuplock standard)

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Tel.: (02) 620-4582, 620-0613

Fax: (02) 620-7194



Client:

Contractor:

Prepared by:S M Ali

Date:24-07-2013

CALCULATION SHEET

(STRUCTURAL)

Page | 6

S No. ItemQty.

No.sU.Wt KNs

Total Wt

KNs.

1 M AO M-lock Std + Cups @ 500mm

c/c.(3Nos 3m, 3 Nos 2.5m,1 No 1m)

1 0.051KN/m 0.9

2 MAO M-lock Ledger + Transom

1.8m Ledger

1.8m ledger handrail

1.6m Ledger handrail1.6m ledger

1.25m Ledger

1.25m ledger handrail

9

2

2/28/2

6/2

4/2

0.068

0.068

0.0610.061

0.045

0.045

0.612

0.136

0.1220.244

0.135

0.09

3 bracing Tube2.5m 9/2 0.085 0.3825

4 Swivel coupler coupler 9 0.016 0.144

Total Dead weight= 2.77KN

Add 5% for Bracing & Fitting = 0.14

Scaffold Board (0.25Kn/m2 x1.31x0.625) =

Toe board (0.25 x 0.23 x 1.31) =

0.205

0.076

Total Dead Load W1= 3.191KNs

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Tel.: (02) 620-4582, 620-0613

Fax: (02) 620-7194



Client:

Contractor:

Prepared by:S M Ali

Date:24-07-2013

CALCULATION SHEET

(STRUCTURAL)

Page | 7

(a) Live load = 2.4 KN/m2 = 2.4 x 1.31 (tributary area) x 1(working level) = 3.144 KN(b) Total Load = DL + LL = 3.191 + 3.144 = 6.34KN

(13)Check for Buckling of Compression Member (MAO M-Lock Vertical)

Assumption

P(DL+LL) = Load due to (Dead Load + Live Load) Per Leg.

Pf = Allowable Load due to Allowable Stress (Fa) per Leg.

DL+LL) = 3.191 + 3.144 = 6.34 KNs.

= Fa xA = 129.33 x 453.45= 58.645KNs.

/4 = 58.645/4 = 14.66 KNs

P (DL+LL)< Pf /4 Hence Safe in Buckling of Compression Member.

(14) Load Carry Capacity of MAO Cuplock Standard per vertical Leg.

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Tel.: (02) 620-4582, 620-0613

Fax: (02) 620-7194



Client:

Contractor:

Prepared by:S M Ali

Date:24-07-2013

CALCULATION SHEET

(STRUCTURAL)

Page | 8

Properties of vertical Standard pipes

Fy (Min Yeid Strength) = 235 N/mm2

Un braced Length L = 2000mm.

Effective Length Leff=KL = 1.0 x 2000=2000mm

Slenderness Ratio Leff /rmin = 2000/16=125.

Euler critical Stress Cc = Sqrt (2x()2xE)/Fy

Sqrt (2x(3.142)2x210000)/235

= 132.83N/mm2.

Leff/rmin < Cc.

Allowable Stress (Corresponding to Leff/rmin = 125)

Fa = {1-( Leff /rmin)2/2 Cc2}x Fy

= {1-(125)2/2 (132.83)2} x 235

= 130.94 N/mm2.

Allowable Load Carry Capacity per vertical Pf= Fa x A= 130.94 x 453.45=59,376.72N

Pf = 59.376 KNs

15) Lateral Stability of Scaffold

Wind Load Analysis as per ASCE 7-05

Design wind pressure P

V = Basic Wind Speed (3-second gust) = 93mph = 150km/h(see attachment-05)=41.67m/s

Exposure 'C' for yanbu as per SAES-A-112

As per ASCE-7 (Table C6-3),the 10-year MRI Wind Speed is 0.84times the 3-second gust.

Hence Wind Velocity V = 41.67m/s x 0.85 = 35.01m/s

Velocity Pressure q z = 0.613 Kz Kzt Kd V2 I

Kz = Velocity Pressure Exposure Coefficient Table 6-3 Exposure C ASCE 7-05

Kzt = Topographic factor = 1.00 as per section 6.5.7 ASCE7-05

Kd = wind directionality Factor = 0.95 table 6.4

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Tel.: (02) 620-4582, 620-0613

Fax: (02) 620-7194



Client:

Contractor:

Prepared by:S M Ali

Date:24-07-2013

CALCULATION SHEET

(STRUCTURAL)

Page | 9

I= Importance Factor = 1.0 As per SSH Addendum #2 section 5.0 Wind Load

Wind Pressure P = qz x G x Cf

G = Gust Response factor = 0.85 as per 6.5.8.1

Cf = Force Coefficient

Cf = 1.2 for round sections, 2.0 for Rectangular Sections (Toe Boards & Planks) As per

SSH Addendum #2 section 5.0 Wind Load

Ac = Area of Circular section (consider Impact area of wind Load).

Ar = Area of Rectangular section (consider Impact area of wind load).

Pc = Wind Pressure on Circular Sections.

Pr = Wind Pressure on Rectangular Sections.

Horizontal Surface Area@ every 2.0m consider:

Ac =(Area of {(HZ Ledger Runner + Hand Rails) + Vertical Standard) x 1.2

=((4x 2.617 x 0.0483) + 2x 0.0483 + 1 x 2.5 x 0.0483) x 1.2

= 0.73 Sq.m

Ar = Area of Toe board

= 0.23 x 2.617= 1.2 Sq.m

Af = Ac + Ar = 0.73+1.2 =1.93sq.m

F= qz x G x(Cfx Af) (since qz = 0.613 x 1.13 x 1 x 0.95 x 41.672 x 1 =1142.7N/m2)

= 1142.7 x 0.85 x 1.93

= 1874 N

= 1.874KN

Horizontal Lateral Wind Force F1 = 1.874 KN

Main Brace requirement

Brace Angle = Tan-1 (2/1.8)= 48.01 deg.

V1= Axial Force in Brace / leg = 1.874/Cos (48.01 deg) = 2.8KN< 5.3KN

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Tel.: (02) 620-4582, 620-0613

Fax: (02) 620-7194



Client:

Contractor:

Prepared by:S M Ali

Date:24-07-2013

CALCULATION SHEET

(STRUCTURAL)

Page | 10

(SWL of Swivel Coupler)

Total Axial Force Transfer in Vertical Standard due to wind load = 2.8KN per leg of a Standard.

Therefore Load Combination = DL+LL+WL

DL/ leg = 3.191 KN from Page 6.

LL/leg = 3.144 KN from Page 6.WL (Axial Force/ leg)= 2.8KN.

Therefore DL+LL+WL = 3.191 + 3.144 + 2.8 = 9.135KN < Pf (Safe.)

Check Couplers on Vertical Bracing

The Vertical Bracing is connected to the Vertical Standard using Swivel Coupler

As per the recommendation of SSH, for wind load in bracing tube, the SWL of couplers shown

in table II 9.2 of SSH may be used.

SWL in Slip available at the connection = 5.3 KN (see attachment-04)

**Max Load in brace due to wind load = 2.8 KN < 5.3 KN SWL at Connection Safe.

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Access scaffoding design